Several publications and patent documents are cited throughout the specification in order to describe the state of the art to which this invention pertains. Each of these citations is incorporated herein by reference as though set forth in full.
Schizophrenia is a serious neuropsychiatric illness estimated to affect 1.3% of the adult population in the United States (Report of the Surgeon General on Mental Health, 1999). The Diagnostic and Statistical Manual-IIIR and IV (DSM-IIIR and DSM-IV) criteria used to diagnose schizophrenia are well known to the skilled artisan. Age of onset is typically between age 15 and 25 for men, and between age 25 and 35 for women. The symptoms typically develop over weeks to months, with a prodromal period preceding the onset of acute psychotic symptoms. The disease is chronic, characterized by episodes of worsening symptoms with active psychosis, followed by periods of relative recovery marked by significant residual impairment. Current treatment is purely symptomatic, with no cure.
The lifetime risk for schizophrenia is 1.5 percent. Risk factors for schizophrenia include a history of schizophrenia in first-degree relatives, birth during the late winter months, and birth trauma. Patients with schizophrenia have substantial amounts of physical and psychological disability, as well as occupational difficulties, with disability equivalent to quadriplegia during periods of worsened symptoms (Report of the Surgeon General on Mental Health, 1999).
Schizoaffective disorder is a related syndrome characterized by the same disability and psychotic symptoms, but with the added feature of prevalent symptoms of mood disturbance. DSM-IIIR and DSM-IV diagnostic criteria are also available to assist in diagnosing this disorder. The lifetime prevalence of schizoaffective disorder is 0.5 to 0.8 percent.
A genetic component for schizophrenia has long been suggested. Family, twin and adoption studies have demonstrated that schizophrenia is predominantly genetic, with a high heritability (McGuffin et al., Br. J. Psychiatry 164:593, 1994). Segregation analyses have failed to clearly support a single model of inheritance, with the suggestion of at least several, possibly interacting, susceptibility loci (Risch, Hum. Genet. 46:222, 1990). Schizophrenia and schizoaffective disorder are often observed within the same family, suggesting that the two disorders may share a common genetic etiology.
Bipolar disorder, another type of neuropsychiatric disorder, is also known as manic-depressive illness and is also described and characterized in DSM-IIIR and DSM-IV. It involves cycles of mania and depression. Signs and symptoms of mania include: extreme irritability and distractibility; excessive euphoric feelings; a sustained period of behavior that is different from the usual behavior; increased energy activity, restlessness, racing thoughts and rapid talking; decreased need for sleep; unrealistic beliefs in one's abilities and powers; uncharacteristically poor judgment; increased sexual drive; abuse of drugs, particularly cocaine, alcohol and sleeping medications; obnoxious, provocative or intrusive behavior and denial that anything is wrong. Signs and symptoms of depression include: persistent sad, anxious or empty mood; feeling of hopelessness or pessimism; feeling of guilt, worthlessness or helplessness; loss of interest or pleasure in ordinary activities; decreased energy, a feeling of fatigue or of being “slowed down”; difficulty concentrating, remembering and making decisions; restlessness and irritability; sleep disturbances; loss of appetite and weight, or weight gain; chronic pain or other persistent bodily symptoms that are not caused by physical disease; and thoughts of death or suicide. Most people with manic-depressive illness can be helped with treatment. However, manic-depressive illness, which is currently diagnosed by symptoms alone, is often not recognized by the patient, relatives, friends and even physicians. If left untreated, bipolar disorder tends to worsen, and the person experiences episodes of full-fledged mania and clinical depression.
Neuropsychiatric disorders, such as schizophrenia, attention deficit disorders, schizoaffective disorders, bipolar disorders and unipolar disorders, differ from neurological disorders in that anatomical or biochemical pathologies are readily detectable for the latter but not the former. Largely as a result of this difference, drugs which have been used to treat individuals with neuropsychiatric disorders, including lithium salts, valproic acid and carbamazepine, have not been predictably effective in treatment regimens across a variety of patients. Treatment regimens are further complicated by the fact that clinical diagnosis currently relies on clinical observation and subjective reports. Identification of the anatomical or biochemical defects which result in neuropsychiatric disorders is needed in order to effectively identify these disorders and to allow the design and administration of effective therapeutics for these disorders. Indeed, there is growing evidence that the episodes of severe psychotic symptoms may lead to irreversible decrements in long-term functioning. Current clinical trials have begun to treat individuals in the prodromal phase, with hopes of limiting the ultimate disability caused by these illnesses. Unfortunately, the diagnosis of neuropsychiatric disorders, such as schizophrenia, attention deficit disorders, schizoaffective disorders, bipolar disorders and unipolar disorders, cannot be accurately made during the prodromal phase. Additionally, the treatments carry a significant risk of serious side effects thus currently limiting this early intervention strategy to individuals known to be at extremely high risk for developing one of these disorders.
Identification of genes associated neuropsychiatric disorders would greatly facilitate the diagnosis and treatment of these illnesses. It is an object of the present invention to provide materials, methods and kits which will aid the clinician in diagnosing and treating such mental disorders. Other objects of the invention are compositions, methods, and kits which will facilitate the identification of pharmaceuticals useful in treating neuropsychiatric disorders.